Distance(A,B) = sqrt((6-1)^2 + (5-4)^2) = sqrt(25+1) = sqrt(26)
Distance(A,C) = sqrt((3-1)^2 + (1-4)^2) = sqrt(4+9) = sqrt(13)
Distance(B,C) = sqrt((3-6)^2 + (1-5^2) = sqrt(9+16) = sqrt(25)
It does not make an isosceles triange (2 sides same length). All side lengths are different.